Hitherto, for a photographic light-sensitive material, a wet development is applied using a developer after photographing. However, in the method, there are following inconveniences and the improvement has been desired.
(1) Because a development, bleaching, fixing, and drying are carried out, a long time is required for the photographic treatment.
(2) Because plural tanks containing a developer are required, a processor cannot be small-sized and lightened.
(3) Troubles such as the replenishment of a developer, the disposal of processing liquids, washing of developing tanks, etc., are required,
For the improvement thereof, photographic light-sensitive materials using a development method by heating (hereinafter, sometimes referred to as "heat development") to a temperature of from 80 to 150.degree. C. are proposed as described in U.S. Pat. No. 3,152,904, U.S. Pat. No. 3,457,075, JP-B-43-4921 (the term "JP-B" as used herein means an "examined Japanese patent publication), JP-B-43-4924, etc. As one example, there is a method of previously incorporating a precursor for a developing agent in a light-sensitive layer, decomposing the precursor by heating to form a developing agent, and developing. In such a heat developing system, the development treatment may be carried out by only application of heat, whereby the treatment can be carried out in a short time and a processor can be small-sized. Furthermore, there are no troubles of the replenishment and the disposal of a developer.
However, in case where the light-sensitive material of this system was applied to a printing light-sensitive material, when 4 plates (blue, green, red, and black plates) were piled up, color discrepancies occurred by the dimensional change occurring during the heat development. To solve the problem, a method of heat treating under a low tension is known as described, for example, in JP-A-60-22616 (The term "JP-A" as used herein means an "unexamined Japanese patent application"), JP-A-64-64883, JP-A-54-158470, and U.S. Pat. No. 2,779,684. By conducting the low-tension heat treatment, the dimensional change between before and after the heat development could be reduced, but accompanied by the heat treatment, inferior planar property (longitudinal wrinkle fault: wrinkles occurring in the longitudinal direction (i.e., the machine direction (MD)) with a pitch of from 10 to 20 cm) occurred. This is a large problem for a photographic support which is required to have a high planar property and as the counterplan thereof, a method of passing a light-sensitive material between rolls is known as described in U.S. Pat. No. 3,663,683. However, in the method, stains occurred on the surface of the photographic support, which was also a large problem. Furthermore, in the cooling process after the heat treatment, an inferior planar property (streaking trouble: galvanized iron sheet-like fine streaks occurring in the longitudinal direction (i.e., the machine direction (MD)) at a pitch of from 1 to 3 cm) occurred.